title: Synthetic studies on the cornexistins: synthesis of (+/-)-5-epi-hydroxycornexistin.
abstract: The synthesis of 5-epi-hydroxycornexistin (44), a diastereoisomer of the herbicidal natural product hydroxycornexistin (2) has been completed. Palladium mediated sp(2)-sp(3) coupling of the stannane 25 and the chloride 31 and ring-closing metathesis of the resulting diene 32 has been used to construct the tricyclic lactone 34a, which possesses the nine-membered carbocyclic core found in the natural product, in good yield. The synthesis of 5-epi-hydroxycornexistin (44) has established the feasibility of using a furan as precursor for the cyclic anhydride unit present in the natural product and has demonstrated the viability of other late-stage transformations that will be used to prepare hydroxycornexistin (2).
authors.affiliation: WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, University Avenue, Glasgow, G12 8QQ, UK. stephenc@chem.gla.ac.uk
authors.forename: J Stephen
authors.initials: JS
authors.lastname: Clark
authors.forename: John M
authors.initials: JM
authors.lastname: Northall
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marlin
authors.forename: Bastien
authors.initials: B
authors.lastname: Nay
authors.forename: Claire
authors.initials: C
authors.lastname: Wilson
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Blake
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Waring
mesh_terms: D000475:Alkenes / Q000737:chemistry; D018360:Crystallography, X-Ray; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D006575:Heterocyclic Compounds, 3-Ring / Q000138:chemical synthesis* / Q000737:chemistry; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry; D009579:Nitrobenzoates / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C533507:5-epi-hydroxycornexistin; D000475:Alkenes; D005663:Furans; D006575:Heterocyclic Compounds, 3-Ring; D007783:Lactones; D009579:Nitrobenzoates; C071795:cornexistin; C008629:4-nitrobenzoic acid; D012825:Silicon